Under physiological conditions, the excitatory amino acids, glutamic and aspartic acid, have an important role as excitatory neurotransmitters. It has been proposed that under certain pathological conditions, there is an excess release of excitatory amino acids which can cause overstimulation of the neurons. Such overstimulation by excitatory amino acids can cause convulsions, behavioral impairments and neuronal loss.
It has been proposed that the neurotoxic effects of excitatory amino acids may have a role in human neurodegenerative diseases such as Parkinson's disease, Pick's disease, Alzheimer's disease, Huntington's chorea, as well as other dysfunctions which occur in ischemia, epilepsy, stroke, and brain and spinal cord trauma or injury.
The excitatory amino acids are known to bind and activate several receptor complexes, including the N-methyl-D-asparatate (NMDA) receptor. NMDA itself can overstimulate neurons and produce convulsions and neuronal loss in animals. Thus, agents which antagonize NMDA can provide neuroprotection in conditions in which excess release of excitatory amino acids occurs.